我的版本:

// Enumerate by nearest space
// Split String value by closest to length spaces
// e.g. for length = 3 
// "abcd efghihjkl m n p qrstsf" -> "abcd", "efghihjkl", "m n", "p", "qrstsf" 
public static IEnumerable<String> EnumByNearestSpace(this String value, int length) {
  if (String.IsNullOrEmpty(value))
    yield break;

  int bestDelta = int.MaxValue;
  int bestSplit = -1;

  int from = 0;

  for (int i = 0; i < value.Length; ++i) {
    var Ch = value[i];

    if (Ch != ' ')
      continue;

    int size = (i - from);
    int delta = (size - length > 0) ? size - length : length - size;

    if ((bestSplit < 0) || (delta < bestDelta)) {
      bestSplit = i;
      bestDelta = delta;
    }
    else {
      yield return value.Substring(from, bestSplit - from);

      i = bestSplit;

      from = i + 1;
      bestSplit = -1;
      bestDelta = int.MaxValue;
    }
  }

  // String's tail
  if (from < value.Length) {
    if (bestSplit >= 0) {
      if (bestDelta < value.Length - from)
        yield return value.Substring(from, bestSplit - from);

      from = bestSplit + 1;
    }

    if (from < value.Length)
      yield return value.Substring(from);
  }
}

...

var list = data.EnumByNearestSpace(150).ToList();